Rhinoviruses, the etiologic agents of the common cold, and polioviruses are represenatives of the picornaviruses--one of the most prominent groups of viruses known, both in terms of variety and incidence of disease and the resultant economic loses to society. They are also one of the smallest and least complex of the human viruses, which makes them attractive for studies to define viral pathogenesis and immunity at the molecular level. We propose to use rhinoviruses and polioviruses as models to investigate the relationship between picornavirus structure and antigenicity. The contribution of the 4 structural polypeptides to the virion capsid antigens will be examined. Mono-specific antiserum to each structural protein, combined with surface labeling methods and peptide mapping will be used to determine which proteins or portions of proteins are exposed on the surface or buried in the capsid. Serologically related rhinoviruses will be studied to establish which of the structural proteins are antigenetically related or identical and the role of these proteins in immunologic cross-reactions. The ability of individual viral polypeptides to induce protective or neutralizing antibody against a number of related rhinoviruses will be evaluated. This work is expected to enhance our understanding of the mechanisms of immune response to viruses, the molecular nature of antigenic variation and antigenic drift, and the feasibility of using viral components as immunizing agents for vaccines.